Radiography Testing Level i and II (2)

8/12/2019 Radiography Testing Level i and II (2)

1/73

@The most common material used to provide protection against

X-rays is:

|D. lead.

^D. VERY GOOD! Lead is very effective, relatively inexpensive,

and compact.

@A curie is the equivalent of:

|B. 1,000 millicuries.

^B. YES! One thousand milli-(one thousandth) curies equal one

curie.

@Assuming that a good radiograph is obtained at a setting of

10

milliamperes in 40 seconds, how much time will be necessary to

obtain one equivalent radiograph if the milliamperage is

change

to 5 milliamperes (all other conditions remain constant)?


2/73

|C. 80 seconds.

^C. TRUE! The inverse square does not apply here and cutting

the

amount of X-rays produced would double the exposure time.

@A graph which expresses the relationship between the

logarithm of the

exposure applied to a photographic material and the resulting

photographic

density is called:

|C. the characteristic curve.

^C. YES! The plot of this function is a characteristic curve

depending on film type and the radiation source.

@Short wavelength electromagnetic radiation produced during

the

disintegration of nuclei of radioactive substances is called:


3/73

|B. gamma radiation.

^B. CORRECT! Gamma and X- radiation of the same wavelength are

identical, but are produced differently.

@A photographic image recorded by the passage of X or gamma

rays

through a specimen onto a film is called a:

|B. Radiograph.

^B. CORRECTO MUNDO! A radiograph is the general term applied

to

all X- or gamma ray photographs.

@The normal development time for manually processing X-ray

film

is:

|D. 5 to 8 minutes in processing solutions at 68 degrees F.

^D. YES! Just right. Actual time will vary between 5 to 8

minutes depending on other factors. 68 degrees F is considered

the

optimum developing temperature.


4/73

@In order to achieve uniformity of development over the area

of

X-ray film during manual processing:

|C. the film should be agitated while in the developer.

^C. YOU'RE RIGHT! Agitation is necessary to replenish depleted

developer

at the film's surface, whether it's mechanical or manual is of

no

consequence.

@When referring to a "2T" or "4T" hole in the ASTM

penetrameter, the T

refers to:

|B. the penetrameter thickness.

^B. ALRIGHTY! 2T equals 2% and 4T equals 4% of the material's

thickness.


5/73

@A sheet of lead with an opening cut in the shape of the part

to

be radiographed may be used to decrease the effect of

scattered

radiation which undercuts the specimens. Such a device is

called:

|A. a mask.

^A. YES INDEEDY! Because it "masks" out everything but the

object being radiographed.

@Two X-ray machines operating at the same nominal kilovoltage

and

milliamperage settings:

|D. may give not only different intensities but also different

qualities of radiation.

^D. AYE! Many other factors besides kilovoltage and

milliamperage determine X-ray intensity and quality.

@Fluoroscopy differs from radiography in that:


6/73

|C. the X-ray image is observed visually on a fluorescent

screen

rather than recorded on a film.

^C. O.K.! This is why it is called fluoroscopy.

@An advantage of the pocket dosimeter type of ionization

chamber used

to monitor radiation received by personnel is:

|B. it provides an immediate indication of dosage.

^B. ABSOLUTELY! It is not a permanent record.

@The density difference between two selected portions of a

radiograph is known as:

|B. radiographic contrast.

^B. ROGER! The selected portions should be from the lightest

and darkest areas of the radiograph to measure the overall

image contrast.

@One requirement for keeping fluorescent screens in good

condition


7/73

is that they must:

|B. not be exposed to intense ultraviolet radiation.

^B. VERY GOOD! UV light depletes the screen of the available

material used to intensify the X- or gamma radiograph.

@In making an isotope exposure in an unshielded area, you find

the

dose rate 6 feet from the source is 1200 mR/hr. What would be

the

dose rate at 24 feet?

|A. 75 mR/hr.

^A. PRECISELY! According to the inverse square law increasing

the distance by 4 results in 1/16th the exposure.

@The intensity of X- or gamma radiation is measured in:

|C. roentgens per unit of time.

^C. EXACTLY! Roentgens only refer to the ionization power of

the radiation for one cubic-centimeter of air.


8/73

@When producing radiographs, if the kilovoltage is increased:

|A. the subject contrast decreases.

^A. OF COURSE! An increase in kilovoltage produces shorter

wavelength X-rays which are less photo-reactive at the film.

@The accidental movement of the specimen or film during

exposure

or the use of a focus-film distance that is too small will:

|C. result in unsharpness of the radiograph.

^C. YOU BET! Just as in conventional photography movement

blurs

the image and reduces its sharpness.

@A properly exposed radiograph that is developed in a

developer solution

at a temperature of 58 degrees F for 5 minutes will probably

be:

|B. underdeveloped.

^B. YEA! 58 degrees F is too cool and five minutes is barely

enough

developing time for 68 degrees F. The combination of the two

results in an underdeveloped radiograph.


9/73

@A good radiograph is obtained using a milliamperage of 15

milliamperes and

an exposure time of 1/2 minute. What exposure time will be

necessary to

produce an equivalent radiograph if the milliamperage is

change to 5 milli-

amperes and all other conditions remain the same?

|B. 1 1/2 minutes.

^B. GOOD! One-third the X-rays means the exposure time must be

tripled.

@Lead screens in contact with the film during exposure:

|A. increase the photographic action on the film largely by

reason

of the electron emission and partly by the secondary X-rays

generated in the lead.

^A. TRUE! THey also reduce fogging due to scattered radiation.


10/73

@The sharpness of the outline in the image of the radiograph

is a measure

of:

|B. radiographic definition.

^B. SURE! Sharpness is a measure of how well an object is

defined against its background.

@An unshielded isotope source gives a dosage rate of 900 mR

per hour

at 10 feet. What would the unshielded dosage rate be at 30

feet?

|C. 100 mR/hr.

^C. YOU'RE RIGHT! According to the inverse square law the

distance is 3 times as much and 3 squared is 9. Therefore,

the output is 1/9 of 900.

@Which has the shortest wavelengths?

|C. 100 kilovolt peak X-rays

^C. CORRECT! These are the shortest. Would 400 kilovolt X-rays

be shorter or longer than 100 kilovolt X-rays?


11/73

@Beta particles are:

|C. electrons.

^C. ALRIGHTY! Electrons ejected from an atom's nucleus are

known as Beta particles.

@A radioactive source with an activity of one curie has:

|D. 370,000,000,000 disintegrations per second taking place.

^D. YESIRREEBOB! This is a tremendous number of

disintegrations, but remember the total number of atoms in a

gram of Cobalt-60 equals approximately 1021 atoms.

@The metal that forms the image on an x-ray film is:

|B. silver.

^B. AYE! Silver bromide is a light sensitive compound that

reduces to black metallic silver after it is exposed to

radiation or light and then developed.


12/73

@Unexposed boxes of x-ray film should be stored:

|B. on edge or end.

^B. CORRECTO MUNDO! Storing film in a vertical position

greatly

reduces the chances of pressure damage due to stacking.

@The lead symbol "B" is attached to the back of the film

holder to

determine:

|B. whether excessive backscatter is present.

^B. RIGHT ON! The resolution of the lead B on the resulting

radiograph indicates the amount of backscatter present

during exposure.


13/73

@The purpose of a dated decay curve is to:

|C. determine the source strength (activity) at any time.

^C. AFFIRMATIVE! This is the logical choice because size and

shielding are set, and atomic decay is not recorded on a

film log.

@Why is cobalt-60 used as a radiation source for medium-weight

metals of thickness ranges form 1.5 to 9 inches?

|C. Because of its penetrating ability.

^C. O.K.! Cobalt-60 emits highly penetrating X-rays of 1.17

and

1.33 MeV.

@During manual film processing, the purpose of the stop bath

is to:

|B. neutralize the developer and stop the developing process.


14/73

^B. ROGER! The stop bath contains a weak acid that "stops" the

developing action.

@A thin metallic sheet (brass, copper, aluminum, etc.) placed

at

the source to reduce effects of softer radiation is known as:

|B. a filter.

^B. VERY GOOD! By reducing the effect of the soft X-rays the

resulting radiograph will be less foggy.

@The reason a "shim" is used in radiographic setup is to:

|C. simulate weld reinforcement.

^C. PRECISELY! This is used to check and calibrate the

radiographic equipment.

@The focal spot size of an x-ray machine must be known in

order to

determine:


15/73

|A. the geometric unsharpness value.

^A. EXACTLY! The exact size must be known. This usually is

measured in hundredths or thousandths of an inch.

@A section with a significant increases in thickness,

variation is

required to be shown on a single radiograph within a desired

film

density range. This may be accomplished by:

|A. increasing kilovoltage.

^A. OF COURSE! By increasing the kilovoltage shorter more

penetrating X-rays are produced, thus enabling a radiograph

of equal contrast to be made of the thicker area.

@The density of a radiograph image refers to:

|D. the degree of film blackening.

^D. YEA! The blackening is a result of clumps of black

metallic

silver.


16/73

@A beam of radiation consisting of a single wavelength is

known as:

|C. monochromatic radiation.

^C. GOOD! Monochromatic literally mans one (mono) color

(chromatic). Generally light and thus radiation are thought

of as having a color (wavelength).

@The image of the required penetrameter and hole on the

radiograph

indicates that the radiograph has the required:

|C. sensitivity.

^C. TRUE! Even if the latitude of the radiograph is wide or

narrow, or the contrast and definition shoddy the imaging of

the penetrameter hole is a measure of radiographic

sensitivity.

@The primary parts of an atom are:

|D. proton, electron, neutron.


17/73

^D. YOU BET! These are the primary atomic parts there are many

others which are very small, but do not concern us here.

@X-rays and gamma rays always travel:

|C. straight lines.

^C. SURE! According to Sir Isaac Newton they will continue

traveling in a straight line forever, until a collision or

gravity affects their course.

@A large source size can be compensated for by:

|A. increasing the source-to-specimen distance.

^A. YEP! By using the inverse square law doubling the distance

decreases the radiation by 2 squared (2x2) or a factor of 4.

@Radiation arising directly from the target of an x-ray tube

or an

accelerator, or from a radioactive source, is usually referred

to as:

|B. primary radiation.


18/73

^B. YOU'RE RIGHT! They are also known as Bremsstrahlung

(German

for braking.) X-rays.

@To produce X-rays, electrons are accelerated to a high

velocity

by an electrical field and then suddenly stopped by a

collision

with a solid body. This body is called:

|C. target.

^C. CORRECT! A target material at the anode then emits a

spectrum of X-rays whose minimum wavelength is controlled by

the kilovoltage.

@The best x-ray efficiency is produced when the target

material has:

|B. a high atomic number.

^B. ALRIGHTY! elements with high atomic numbers are the

heavier, more dense elements and make excellent X-ray

emitters.


19/73

@In a fluoroscopic inspection system using a 15 inch

source-to-material

distance and 2 inch material-to-screen distance, transverse

vibration of

which item will cause the most image blurring?

|C. Material vibration.

^C. AYE! The source and screen are in a fixed position and

should not vibrate; however their vibrating does not create

the most image blurring.

@If a fluorescent screen is accidentally exposed to

unattenuated

x-rays, which of the following occurs?

|C. The screen is essentially undamaged.

^C. RIGHT ON! If the screen were greatly effected by

attenuated

or unattenuated X-rays their repeated use would be severely

limited and this is not the case.


20/73

@Which of the following is an advantage of a fluoroscopic

system

when compared to a radiographic system?

|B. Live image presentation for immediate viewing.

^B. CORRECTO MUNDO! A "real-time" radiographic system has many

advantages including eliminating on going film and

development cost, but lacks the sensitivity of film.

@A fluoroscopic installation utilizing fluorescent screen

requires:

|B. Lead glass, mirrors, or other means for transmitting the

fluorescent image without subjecting the operator to

x-radiation.

^B. YES INDEEDY! These are needed to shield andprotect the

operator from nonconverted X-rays passing through the

screen.


21/73

@In X-radiography, the ability to penetrate the test object is

governed by:

|C. kilovoltage.

^C. AFFIRMATIVE! Kilovoltage determines the minimum wavelength

of the spectrum of X-rays produced. Increasing kilovoltage

produces short wavelength more penetrating X-radiation.

@Which of the following types of radiation is emitted by

cobalt-60 and used

in nondestructive testing?

|B. Gamma rays.

^B. ABSOLUTELY! Gamma rays are the result of the atomic

disintegrations occurring in Cobalt-60.

@The term used to describe the loss of excess energy by the

nucleus of radioactive atoms is called:

|A. decay (disintegration).

^A. ROGER! It is the atomic decay (disintegration) that

creates


22/73

gamma rays which is energy lost by the material in the form

of radiation.

@X-rays, gamma rays, and alpha particles all have one thing in

common-they are all:

|D. ionizing radiations.

^D. VERY GOOD! All three are capable of ionizing (creating

negative or positive ions) elements or compounds.

@The term used to express the number of curies of

radioactivity per

gram or ounce of source weight is:

|C. specific activity.

^C. PRECISELY! The specific activity is the curies per gram or

ounce of material. One curie equals 3.7 x 1010 atomic

disintegrations per second.

@Atoms, molecules, and various subatomic particles which carry

either a positive or negative electrical charge are called:


23/73

|C. ions.

^C. EXACTLY! Compounds are composed of only molecules, all

electrons are negative, and all protons are positive.

@Approximately what percent of the original radioactivity is

left

after six half-lives?

|D. 2

^D. YEA! This is an approximation it is actually one 64th or

1.56 percent.

@The radiation intensity of a radioisotope:

|B. decreases with time.

^B. GOOD! The half-life is a measure of this decrease.


24/73

@Low voltage X-ray tubes are generally fitted with windows

made of:

|B. beryllium.

^B Correct! Beryllium allows all but the longtest wavelength

x-

rays to pass through it.

@A monochromatic X-ray beam:

|D. is a beam consisting of a single wavelength.

^D. YOU'RE RIGHT! Mono means one or single and chromatic

refers to the color or wavelength.


25/73

@The general method of producing X-rays involves the sudden

deceleration of high velocity electrons in a solid body called

a:

|C. target.

^C. CORRECT! The focusing cup, filament, and cathode produce

and

direct the electron beam.

@If it were necessary to radiograph a 7-inch thick steel

product,

which of the following gamma-ray sources would most likely be

used?

|A. Cobalt-60

^A. ALRIGHT! Cobalt is suitable for radiographing steel above

3-4 inches thick and has a rated penetrating power of 1.17

and 1.33 MeV respectively.

@The absorption of gamma rays from a given source when passing

through matter depends on:


26/73

|A. the atomic number, density, and thickness of the matter.

^A. YES! The thickness, atomic number, and material

density all effect the absorption of both gamma and X-rays.

@The velocity of electrons striking the target in an X-ray

tube

is a function of:

|C. the voltage difference between the cathode and anode.

^C. RIGHT ON! The voltage potential between the cathode and

anode is responsible for electron velocity.

@The uneven distribution of developed grains within the

emulsion

of a processed X-ray film causes the subjective impression of:

|A. graininess.


27/73

^A. CORRECT! Also note the faster the film the larger the

individual

silver salts (grains). Thus fast film tends to be grainier.

@Of the following, the source providing the most penetrating

radiation is:

|C. 15 MeV x-ray betatron.

^C. YES! A 15MeV X-ray betatron is a linear accelerator

whose beam strength is 12 times that of Cobalt the next most

penetrating source on this list.

@The focal spot in an X-ray tube:

|D. should be as small as possible without unduly shortening

the

life of the tube.

^D. O.K.! A smaller focal spot creates a narrower beam of X-

radiation and raises the definition of the radiograph.


28/73

@In an X-ray tube, the filament and focusing cup are the two

essential parts of the:

|B. cathode.

^B. ABSOLUTELY! The filament is the source of the electrons

and

the focusing cup aims them onto the target anode.

@The quantity of radiation which will produce, by means of

ionization, one electrostatic unit of electricity in 0.001293

grams of dry air is known as:

|C. a roentgen.

^C. CORRECT! 0.001293 grams of dry air is equivalent to one

cubic centimeter of dry air at sea level.

@The specific activity of an isotopic source is usually

measured

in:

B. curies per gram.

^B. VERY GOOD! The curies per gram is the measure of specific

activity. One curie equals 37,000,000 disintegrations per


29/73

second.

@Which of the following isotopes has the longest half-life?

|D. Cesium-137

^D. PRECISELY! Cesium-137 with a half-life of 30 years in the

longest of this group.

@The primary form of energy conversion when electrons strike a

target in an X-ray tube results in the production of:

|D. heat.

^D. EXACTLY! For example: only 3% of a 300 keV X-ray tube's

total energy is converted to X-rays. The other 97% is

released as heat.

@An X-ray film having wide latitude also has, by definition:


30/73

|B. low contrast.

^B. YES! X-ray films with a narrow latitude by definitions are

high contrast.

@The purpose for circulating oil in some types of X-ray tubes

is:

|D. to dissipate heat.

^D. GOOD! Because 97% or more of the energy of an X-ray tube

is

given off as heat circulating oil is used for cooling.

@An X-ray tube with a small focal spot is considered better

than

one with a large focal spot when it is defined to obtain:

|B. better definition.

^B. TRUE! The smaller the focal spot the better the

definition.


31/73

@One method of reducing radiographic contrast is to:

|C. decrease the wavelength of the radiation used.

^C. YOU BET! Shorter wavelength X-rays are more penetrating ,

but less photographically active and produce high contrast

radiographs.

@Thin sheets of lead foil in intimate contact with X-ray film

during exposure increase film density because:

|D. they emit electrons when exposed to X- and gamma radiation

which help darken the film.

^D. CORRECT! These electrons are photographically active and

intensify the exposure and increase the darkening of the film.

@X-ray tubes are often enclosed in a shockproof casing in

order

to:

|B. protect the operator from high-voltage shock.

^B. YOU'RE RIGHT! Do to the high voltages involved an


32/73

electrically insulated casing is required to protect the

operator.

@An X-ray tube is rated for a maximum of 250 kVp. This tube

may

be operated at a maximum of:

|A. 250,000 volts peak voltage.

^B. Effective voltage! Not conventional radiographic term.

What

does the "p" stand for?

@In X-ray radiography, alternating current must be changed to

pulsating direct current in order to satisfy the need for

unidirectional current. This change may be accomplished by:

|B. rectifiers.

^B. YES! The half wave rectifier converts the ac to pulsing dc

current.


33/73

@When radiographing to the 2-2T quality level, an ASTM

penetrameter

for 2.5 inch steel has a thickness of:

|D. 50 mils.

^D. CORRECT! 50 mils. equals .05 inches or 2 percent of 2.5

inches, computed as 2.5 x .05 or 50 mils., or 50 thousandths

of an inch.

@Valve tubes are used in X-ray equipment to:

|A. provide necessary rectification.

^A. Correct! yes the valve tubes are used to convert ac to

pulsing dc current.

@A good cobalt-60 radiograph is made on a 3 inch steel casting

using an

exposure time of 10 minutes and a source-to-film distance of

36 inches.

It is necessary to change the source-to-film distance to 24

inches, what

exposure time would produce a similar radiograph if all other


34/73

conditions

remain the same?

|B. 4.4 minutes.

^B. Yes! 3 ft. squared equals 9, and 2 ft squared equals 4.

4 /9 = 4/9 x 10 = 4.444...

@When sharp, black bird-foot shaped marks which are known not

to

correspond with any discontinuities appear at random on

radiographs,

they are probably caused by:

|C. static charges caused by friction.

^C. Yes! The electrical discharge of static electricity

exposes

crystals.

@The adjustment of tube current in conventional X-ray tube

circuits is made by:

|A. adjusting the filament heating current.

^A. CORRECT! This increases the number of electrons produced

and


35/73

is a function of amperage.

@In comparison with lower-voltage radiographs, high-energy

radiographs show:

|B. greater latitude.

^B. CORRECT! High penetrating short wavelength X-rays are less

photographically active.

@Filters used at the port of the X-ray tube:

|D. filter out "soft" radiation to provide a more homogeneous

X-ray beam.

^D. Yes! The short wavelengths pass through with minimal

attenuation. The longer wavelengths "softer" X-rays

create scatter radiation and film fog.

@An ASTM penetrameter for use when inspecting a one-half inch

thick steel plate to the 2-2T quality level using a 15 inch

source-to-film distance would be made of:

|C. 10 mil thick steel.

^C. VERY GOOD! 10 mils. is the equivalent to .01 inches or 2

percent of .5 inches.


36/73

@Filters placed between the x-ray tube and specimen tend to

reduce scatter radiation undercutting the specimen:

|A. by absorbing the longer wavelength components of the

primary

beam.

^A. EXACTLY! The longer wavelength "soft" X-rays increase

scatter radiation and can fog the resulting radiograph.

@Besides serving as a filter, screens of high atomic number,

such

as lead and lead antimony, also:

|B. provide some image intensifying action.

^B. OF COURSE! By releasing electrons that photographly react

with the film.

@The range of thickness over which densities are obtained that

are satisfactory for interpretation is a measure of the:

|C. latitude of a radiograph.

^C. GOOD! The range of thickness over which densities are

satisfactory for interpretation is known as latitude.


37/73

@Almost all gamma radiography is performed with:

|B. iridium-192 or cobalt-60.

^B. TRUE! Thulium-170 and radium are rarely used.

@Images of discontinuities close to the source side of the

specimen become less clearly defined as:

|B. the thickness of the specimen increases.

^B. SURE! The increase in material between the discontinuity

and the film reduces the definition.

@The inherent filtration of an x-ray tube is a function of:

|A. the thickness and composition of the x-ray tube port.

@X-ray films with large grain size:

|C. have higher speeds than those with a relatively small

grain

size.

@As the effective energy of the radiation increases up to


38/73

about

250kV:

|A. film graininess increases.

@The specific activity of cobalt-60 depends on:

|A. the time the material has been in the reactor.

^A. YES! More Cobalt-59 is converted to Cobalt-60.

@The most commonly used target material in an x-ray tube is:

|D. tungsten.

^D. RIGHT! Tungsten is commonly used because of its density

and

high melting point.

@The purpose for including a disc-shaped target that rotates

rapidly during operation in some x-ray tubes is to:

|C. increase the permissible load.

^C. CORRECT! By cooling the target anode rotation allows

higher

voltages or loads to be used without over heating and

melting the target.


39/73

@A device which is basically a combination of magnet and

transformer designed to guide and accelerate electrons in a

circular orbit to very high energies is called a:

|C. betatron.

@Two isotopic sources of a given strength have two different

specific activity values. The source with the higher specific

activity value will:

|A. be of smaller physical size than the source with a lower

specific activity.

^A. CORRECT! Specific activity is measured by curies per gram,

thus, if source strength is equal the higher specific

activity source will be smaller and weigh less.

@A gas-filled region located in an electrical field created by

electrodes across which a potential difference is applied

forms

the major portion of:

|D. an ionization chamber.


40/73

^D. ABSOLUTELY RIGHT! X-ray tubes contain a vacuum.

@Two serious obstacles to high-sensitivity fluoroscopy are:

|B. the limited brightness and large grain size of

fluoroscopic

screens.

^B. CORRECT! The limited brightness and grainy image make

fluoroscopy less sensitive.

@In general, the quality of fluoroscopic equipment is best

determined by:

|B. penetrameter sensitivity measurements.

@In fluoroscopic testing, a fundamental difficulty is the

relative low brightness level of the images. One method for

increasing brightness utilizes one of the following which

converts light energy from the initial phosphor surface to

electrons which are accelerated and focused onto a smaller

fluorescent screen.

|C. Image amplifier or intensifier.


41/73

@A general rule governing the application of the geometric

principles of shadow formation states that:

|D. the central ray should be as nearly perpendicular to the

film as possible, to preserve spatial relationships.

^D. CORRECT! Any other angle increases the geometric

distortion

of the object being radiographed.

@In order to utilize the principles of geometric enlargement

(placing the film at a distance from the specimen):

|B. the source of radiation must be extremely small.

^B. CORRECT! This would increase definition.

@The radiographic absorption of a material will tend to become

less dependent upon the composition of the material when:

|A. the kilovoltage is increased.

^A. CORRECT! Shorter wavelength X-rays are produced and their

alternation is more dependent upon material thickness.

@The formula (milliamperes X times)/(distance squared is:


42/73

|D. the exposure factor.

@The load that can be handled by an x-ray tube focal spot is

governed by:

|B. the size of the focal spot and the efficiency of the

cooling

system of the anode.

@X-ray exposure holders and cassettes often incorporate a

sheet

of lead foil in the back which is not in intimate contact with

the

film. The purpose of this sheet of lead foil is:

|B. to protect the film from backscatter.

@A lead sheet containing a pinhole may be placed halfway

between

the X-ray tube and the film in order to:

|A. determine the approximate size of the focal spot.

@The most common way of cooling the anode of a high-power

X-ray

tube is:


43/73

|C. cooling by circulation of water or oil in the anode.

@In certain cases, it may be advantageous to pack lead shot

around a specimen. The purpose for doing this is:

|D. to decrease the effect of scattered radiation undercuttin

the specimen.

@The mottling caused by diffraction when radiographing fairly

large-grained metallic specimens can be reduced and in some

cases

eliminated by:

|C. raising the kilovoltage and using lead foil screens.

^C. CORRECT! Raising KV produces shorter wavelength X-rays and

the lead screens filter out the less penetrating shorter

wavelengths.

@When radiographing steel with a thickness less than one inch:

|B. a 250 kV X-ray machine would give greater radiographic

sensitivity than cobalt-60.

@A radiograph made with an exposure of 12mA per minute has a


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density of 0.8 in the region of maximum interest. It is

desired

to increase the density to 2.0 in this area. By reference to a

characteristic curve of the film, it is found that the

difference

in log E between a density of 0.8 and 2.0 is 0.76. The

antilogarithm of log 0.76 is 5.8. What must the new exposure

time be to produce a radiograph with a density of 2.0?

|C. 69.6 mA per minute

@The absorption of radiation by a material varies:

|D. in an approximately exponential manner with the thickness

of

the material.

@In order for a radiograph to have a penetrameter sensitivity

of

2-2T or better:

|B. the radiographic procedure must be able to define the 2T

hole in a penetrameter which is 2 percent of the thickness

of the specimen.

@For practical purposes, the shape of the characteristic curve


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of

an X-ray film:

|B. is independent of the quality of X- or gamma radiation.

@The term which describes the total absorption of the useful

beam

caused by the X-ray tube wall, the wall of the tube housing,

and

any material between the tube and housing is:

|D. inherent filtration.

@The interval between the time a film is placed in a fixer

solution and the time when the original diffuse, yellow

milkiness

disappears is known as:

|A. clearing time.

^A. CORRECT! This is followed by an equal amount of time for

hardening.

@Improper geometric factors, poor contact between film and

lead

foil screens, and graininess of film are possible causes of:


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|B. poor definition.

@In fluoroscopy the most common means for minimizing operator

fatigue is to:

|D. change operators periodically.

@Which of the following X-ray generators would produce the

narrowest cone of X-radiation?

|C. 25MeV

@A radiograph is taken at a voltage of 500 kV. If the voltage

is

increased with a resultant increase in the energy of radiation

while all other conditions remain the same:

|D. there will be little significant change in the graininess

of

the film.

@A radiograph of a steel weldment is made using a 15 MeV

betatron. When the radiograph is developed, there is an

overall


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film mottling. A possible cause for such mottling is:

|C. failure to use a lead screen during exposure.

@A basic difference between a radiograph and a fluoroscopic

images is:

|B. the fluoroscopic image is a positive whereas the

radiograph

is a negative transparency.

^B. CORRECT! It is also less sensitive.

@The quantity of radiation striking a unit area of film:

|A. is the product of radiation intensity and time.

@Which of the following factors will not materially influence

the

image density of a radiograph?

|B. The size of the film

^B. CORRECT! The size of the film is not a factor influencing

film density.


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@A 1,000 kVp X-ray machine used in conjunction with a lead

foil

screen has an approximate practical thickness limit of:

|C. 5 inches of steel or its equivalent.

@Because of geometrical factors such as source size,

source-to-specimen distance and specimen-to-film distance,

there

can be a lack of perfect sharpness at the edges of

indications.

The unsharpness caused by geometrical factors may be referred

to

as the:

|B. penumbral shadow.

@Two factors which greatly affect the suitability of the

target

material in an X-ray tube are:

|D. atomic number and melting point.

^D. CORRECT! Targets made from elements with high atonic

numbers are more efficient and high operating temperatures


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require a high melting point.

@The reason the exposure time must be increased by a factor of

four when the source-to-film distance is doubled is:

|C. the intensity of radiation is inversely proportional to

the

square of the distance from the source to the film.

^C. CORRECT! This is known as the inverse square law.

@The approximate radiographic equivalence factors for steel

and

copper at 220kV are 1.0 and 1.4 respectively. If it is

desirable

to radiograph a 0.5-inch plate of copper, what thickness of

steel

would require about the same exposure characteristics?

|A. 0.7 inches of steel

^A. CORRECT! Or .5 x 1.4 x 1.0


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@Which of the following technique variables is most commonly

used

to adjust subject contrast?

|C. Kilovoltage

^C. CORRECT! Adjusting the KV increases or decreases the

penetrating power of the X-rays produced and thus the

resulting image contrast.

@Films that are left between lead screens too long in a

high-temperature and high-humidity atmosphere may:

|B. become fogged.

^B. CORRECT! Fogging occurs because of a chemical change in

the

silver bromide crystals.

@The quantitative measure of film blackening is referred to

as:

|B. photographic density.

^B. CORRECT! The instrument used to measure film density is

called a densitometer.


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@A curve relating density with the logarithm of exposure or of

relative exposure is called:

|C. an H & D curve.

@Which of the following instruments would exhibit the best

sensitivity and most likely be used to detect small leaks in a

radiation barrier?

|C. A Geiger counter

^C. CORRECT! A geiger counter is more sensitive and gives an

immediate indication of radiation.

@At voltages above 400 kV, the use of lead to provide

protection

may present serious problems. If this should be a serious

problem, which of the following materials would most likely be

used as a substitute?


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|B. Concrete

^B. CORRECT! Concrete is not only effective, but inexpensive

as

well.

@A qualitative term often used to indicate the size of the

smallest detail which can be seen in a radiograph is:

|A. radiographic sensitivity.

@The slope (steepness) of a characteristic curve is a measure

of:

|D. film contrast.

@A special radiographic method requiring two radiographs taken

during separate exposures from two different positions to give

the visual impression of a three-dimensional display when

viewed

in an optical device simultaneously is referred to as:

|C. stereoradiography.

^C. CORRECT! Stereo means two.


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@The depth of a discontinuity may be estimated by making two

exposures on a single film from two different positions of the

X-ray tube. The depth of the discontinuity is computed from

the

shift in the shadow of the discontinuity with respect to the

images of fixed markers on the front and back of the specimen.

The method is referred to as:

|D. the parallax method of depth location.

@Constant agitation of the developer during the development

process by means of mechanical stirrers or circulating pumps

may:

|C. cause undesirable, preferential flow of developer

along certain paths.

@The activity of the fixer diminishes after being used for a

period of time because:

|C. the fixer solution accumulates soluble silver salts.

^C. CORRECT! This contamination results in the diminishing

activity of the solution.


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@In processing radiographs, the hourly flow of water in the

wash

tank should be:

|B. four to eight times the volume to of the tank.

@A zinc cadmium sulfide fluoroscopic screen which is

continually

exposed to bright daylight, sunlight, or other sources of

ultraviolet radiation will:

|B. become discolored and lose some of its brilliance.

@Increasing the X-ray or gamma-ray energy will:

|D. have little effect on the shape of a characteristic curve.

@As the development time increases:

|A. the characteristic curve grows steeper and moves to the

left.


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@A distinctive characteristic of high-voltage radiography is:

|C. it is applicable to comparatively thick or highly

absorbing

specimens.

^C. CORRECT! High voltages are necessary to accelerate the

electrons fast enough in order to produce the shortest

wavelength most penetrating X-ray possible.

@Lead screens are used for almost all exposures when using:

|C. high-voltage radiography.

^C. CORRECT! This eliminates most of the shorter less

penetrating wavelengths that are produced when using

high-kilovoltage.

@The fact that each solid crystalline substance produces its

own

characteristic X-ray pattern is the basis for:

|D. X-ray powder diffraction examination.

@Which of the following glasses would most likely be used as


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an

X-ray barrier window on fluoroscopic equipment?

|B. Lead glass

^B. CORRECT! The attenuation properties of lead give the glass

shielding features.

@The maximum practical speed of scanning a test object for

conventional fluoroscopic inspection has been estimated to be:

|D. about 3 inches per second.

@When other operating conditions are held constant, a change

in

tube current causes a change in radiation intensity emitted

from

an X-ray tube, the intensity being approximately proportional

to

tube current. What is the primary factor that prevents this

from

being exactly proportional?

|A. The voltage and voltage waveform of an X-ray machine

transformer varies with load.


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@When viewing a radiograph, an image of the back of the

cassette

superimposed on the image of the specimen is noted. This is

most

likely due to:

|D. Backscatter.

^D. CORRECT! Radiation scattered onto the back of the film

cassette causes this, a lead "B" is placed on the

back of the film to measure back scatter radiation.

@A special form of scatter due to X-ray diffraction effects in

a

specimen with large grains will result in:

|B. a radiograph of mottled appearance.

@The half-value layer of lead for cobalt-60 is approximately

0.5

inch. If the radiation level on the source side of a 1.5 inch

lead plate is 64 R/hr, the radiation level on the opposite


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side

is:

|A. 8 R/hr.

^A. CORRECT! Calculated as 64 x 1/2 x 1/2 x 1/2 = 8

@Which of the following is not a factor in determining subject

contrast?

|C. Type of film used

^C. CORRECT! The type of film used has inherent contrast

qualities known as "film contrast" which has no relation to

subject contrast.

@If an exposure time of 60 seconds and a source-to-film

distance

of 4 feet is necessary for a particular exposure, what

exposure

time would be needed for an equivalent exposure if the

source-to

-film distance is changed to 5 feet?

|B. 94 seconds


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^B. CORRECT! According to the inverse square law 5 squared/4

squared = 1.5625 x 60 = 93.75 or 94 seconds.

@In order to increase latitude so that thick and thin portions

may be radiographed at reasonable viewing

densitiesNsimultaneously:

|C. the film cassette may be loaded with two films of

different

speeds.

^C. CORRECT! Since latitude is an inherent property, as is

film

contrast, the only way to increase it is to use two films

with different speeds.

@Developer solution should be discarded when the quantity of

replenisher

added equals:

|B. two to three times the original quantity of developer.

^B. CORRECT! Once two or three replenisher supplements have

exhausted the developer it becomes too contaminated to

revive.


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@If a specimen were radiographed at 40 kV and again at 50 kV

with

time compensation to give the radiographs the same density,

which

of the following statements would be true?

|C. The 50 kV exposure would have a lower contrast and a

greater

latitude than the 40 kV exposure

^C. CORRECT! Because the kV X-rays are harder and have less

photoactive capabilities.

@A 250 kVp X-ray machine used in conjunction with a lead foil

screen has an approximate practical thickness limit of:

|B. 2 inches of steel or its equivalent.

@The degree of concentration of the radioactive material in a

gamma-ray source is referred to as:


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|A. the specific activity of the source.

^A. CORRECT! And it's measured as curies per gram.

@In million-volt radiography, filtration at the tube:

|D. offers no improvement in radiographic quality.

^D. CORRECT! Filtration of such a powerful X-ray beam at the

tube offers no improvement in the radiographic quality.

@The energy of gamma rays is expressed by which of the

following

units of measurement?

|D. Kiloelectron volt (keV) or million electron volt (MeV)

^D. CORRECT! KeV and MeV are measurements of gamma ray energy.

@While using an X-ray tube for radiography, the operator

wishes

to increase the radiation intensity. To do so, the:

|B. tube current should be increased.


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^B. CORRECT! Raising tube current or milliamperage increases

X-

ray intensity.

@Because of geometrical factors such as source size,

source-to-specimen distance, and specimen-to-film distance,

there

can be a lack of perfect sharpness at the edges of

indications.

The unsharpness caused by these factors may be referred to a

the:

|B. penumbral shadow.

^B. CORRECT! By controlling these factors the penumbral shadow

can be reduced and sharpness increased.

@The main purpose of the X-ray generator controls on the

equipment is:

|B. to enable the operator to obtain the intensity, quality,

and

duration of exposure desired.

^B. CORRECT! Intensity is controlled by milliamperage, quality

by kilovoltage, and exposure duration by a timer or switch.


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@Fluoroscopic screens, as mounted and used, are easily damaged

by

which of the following?

|B. Exposure to ultraviolet radiation or sunlight

^B. CORRECT! Sunlight and ultraviolet light drain the amount

of

fluorescent material available for visible light production

during radiography.

@When X rays, gamma rays, light, or electrons strike the

photographic emulsion, a change takes place in the silver

halide

crystals. This change is referred to as:

|C. latent image.

^C. CORRECT! This is a chemical change which is not apparent

until the film is processed.

@If one curie of iridium-192 produces a dose rate of 5900 mR

per


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hour at one foot, how may mR will ten curies produce at the

same

distance?

|D. 59,000

^D. CORRECT! Since the distance is equal a ten curie source is

exactly ten times as intense as a one curie source.

@With respect to quality, what three factors must be

considered

in selecting a source-to-film distance?

|D. Source size, specimen thickness, geometric unsharpness

^D. CORRECT! All three are important quality factors.

@On a radiograph of a pipe weld there is a very light

irregularly-shaped

small image in the weld. This image would most likely be due

to the

presence of:

|C. tungsten inclusion.


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^C. CORRECT! Tungsten is more dense and attenautes the beam

more than the surrounding material resulting in a very light

image, and is irregular in shape.

@A larger physical size source may produce an equivalent

quality

radiograph if:

|A. the source-to-film distance is increased.

^A. CORRECT! This in essence reduces its physical size as it

appears from the viewpoint of the specimen.

@A light image of a backing "B" on a processed radiograph is

probably caused by:

|B. backscatter.

^B. CORRECT! A lead backscatter is attached to the back of the

film to measure backscatter and when exposed results in

a light image.


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@Cobalt-59 becomes cobalt-60 when it is placed in a nuclear

reactor where it captures:

|B. a neutron.

^B. CORRECT! And thus increases the atomic weight by one.

@When a faster speed film is substituted for a slower one to

improve the economics of the exposure, which of the following

conditions occur?

|C. The image resolution will be reduced

^C. CORRECT! The resulting image is grainier.

@For a given change in the radiation exposure, film contrast

is

the inherent ability to show:

|A. a difference in density.

^A. CORRECT! It has nothing to do with graininess although

faster (large grain) films usually have lower contrast than

slower (fine grain) films.


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@The ability of a material to block or partially block the

passage of X rays and gamma rays is referred to as:

|C. absorption.

^C. CORRECT! Also referred to as attenuation.

@Source size, specimen thickness, and source-to-specimen

distance

are the three factors that determine the:

|D. unsharpness recorded on the radiograph.

^D. CORRECT! All three are factors directly related to image

sharpness.

@The range of specimen thicknesses that can be adequately

recorded on the radiograph is referred to as the:

|B. latitude of the radiograph.

^B. CORRECT! Latitude is the range of thicknesses that can be

adequately recorded on the radiograph.


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@Approximately how long would it take for a 10 curie cobalt-60

source to decay to 2 1/2 curies?

|C. 10.6 years

^C. CORRECT! Since the half-life of Cobalt-600 is 5.3 years it

would take two half lives to reduce a 10 curies source to a

2.5 curie source.

@The "photoelectric" effect involves:

|C. complete absorption of a photon.

^C. CORRECT! Part of the photon energy is used in ejecting an

electron and the remainder imparts velocity to the ejected

electron.

@Radiographic undercutting is caused by:

|A. side scatter.

^A. CORRECT! It is also caused by internal scatter and can

present problems when radiographing irregularly shaped

objects.


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@The developer solution is:

|B. alkaline.

^B. CORRECT! The stop bath is acid.

@A general rule governing the application of the geometric

principles of shadow formation states that:

|D. the central ray should be a nearly perpendicular to the

film

as possible, to preserve spatial relationships.

^D. CORRECT! Any angel other than 90 degrees increases

geometric distortion of the images on the radiograph.

@An X-ray film having wide latitude also has, by definition:

|B. low contrast.

^B. CORRECT! Narrow latitude films have high contrast.

@The projected area of the target of an X-ray tube is called:

|C. effective focal spot.

^C. CORRECT! The effective focal spot is either equal to or


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less

than the actual focal spot.

@The slope of the H & D curve of a radiographic film is

called:

|C. gamma or gradient.

|B. fluorescent screen exposures.

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

@The half-life of radioactive cesium-137 is nearest:

|C. 30 years.

^C. CORRECT! Its rays have an average penetration power of

664 keV.

@An iridium-192 gamma-ray source has an approximate practical

thickness limit of:

|A. 3 inches of steel or its equivalent.

@The half-life of radioactive cesium-137 is nearest:


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|C. 30 years.

^C. CORRECT! Its rays have an average penetration power of

664 keV.

@An iridium-192 gamma-ray source has an approximate practical

thickness limit of:

|A. 3 inches of steel or its equivalent.

@Unwanted inclusions in a part will appear on a radiograph as:

|D. either a dark or light spot or area depending on the

relative

absorption ratio of the part material and the inclusion

material.

@The radiation quality of a gamma-ray source is:

|B. determined by the isotope involved.

@A graph showing the relation between material thickness,

kilovoltage,

and exposure is called:

|B. an exposure chart or technique chart.

@The formula for determining permissible accumulated personnel

dose is:

|C. 5 (N-18)

@Penetrameters for _____ are considered Group 1 Materials and

need


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not have an identification notch.

|C. Stainless steel.

@What is sometimes used to change the alternating current from

the high

voltage transformer to direct current for the purpose of

increasing the

X-ray machine output?

|A. Rectifier.

@The velocity of all electromagnet radiation is:

|A. 186,000 miles per second.

@A Cobalt-60 gamma ray source has an approximate practical

thickness limit of:

|C. 9 inches of steel or its equivalent.

@The fact that gases, when bombarded by radiation, ionize and

become electrical conductors make them useful in:

|D. radiation detection equipment.

@The gamma-ray intensity at one foot from a one curie source

of

radioactive cobalt-60 is nearest:

|A. 15 roentgens per hour.

@The slope of a straight line joining two points of specified

densities on a characteristic curve of a film is known as the:


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|C. average gradient.

@A voltage selector consisting of an iron core transformer

with a

single winding having a series of taps at various points on

the

winding is called:

|C. an autotransformer.

@The amount of unsharpness or blurring of a radiograph is:

|B. directly proportional to the size of the focal spot and

inversely proportional to the source-to-object distance.

Documents

Radiography Testing Level i and II (2)